The term "wiring harness" is usually employed to describe a structure of conductor wires which structure is produced separately from the apparatus in which it will ultimately be incorporated. That is, the term is ordinarily not used to describe wiring that is formed in situ in the chassis in which it will be used. The several wire ends that are incorporated in a harness may be left unconnected so that they can be connected to terminals within the chassis after the harness is installed. Or they are connected to a terminal. That terminal may be an individual one, or it may be one of many terminals that are housed together in a connector which is to mate with another connector once it is installed as a component in the unit for which it was made. It is usual for each connector and for each terminal and for each wire to be given an individual identifier. That identifier can be a name or a letter or a number or a color. Each wire extends from a first place to a second place, and for convenience here, the end of the wire that terminates at the first place is called the "first end" and the end that terminates at the second place is called the "second end".
When a number of substantially identical wiring harnesses are to be produced, it is usual to produce them on a structure called a "harness forming board" or something similar. The forming board may or may not be flat. In any event, its shape is arranged so that conductor wire can be fastened to it temporarily, one at a time, so that each end of each wire begins and ends at a place that corresponds to the points at which those wires are to be connected when the harness is removed from the board and placed in the apparatus for which it is made. Wiring harnesses are often very complex. They may consist of hundreds of wires and many connectors, and the connectors may be spaced from one another in many different directions.
The construction of a complex wiring harness is often tedious, and may present many opportunities for error.